This patch contains very minor fixes for the PyO3 0.27 series:

• Workaround a rustc 1.92+ crash compiling PyO3 with both debug assertions and optimizations enabled.
• Fix runtime crash when subclassing dicts on PyPy and GraalPy.

There are also a number of documentation improvements applied across the codebase.

Thank you to the following contributors for the improvements:

@davidhewitt @dependabot[bot] @MusicalNinjaDad @pkalivas @tpoliaw @Tpt